Current Electricty Flashcards
Current
The flow of electrons in a wire
Circuit
A continuous loop (usually metal) that is needed for electrons to flow in order for electricity to flow
Voltage
Potential difference : the amount of force with which the battery can push electrons
From which side does the battery push electrons
Negative side , around circuit, back to positive
Resistors
Slow down the flow of current, turns electrical energy into heat energy
Eg thin wire in a bulb
Series
All the current that flows through one bulb also has to flow through the other - a continuous loop.
If one bulb fails, the other won’t light
Parallel
The current flowing in the circuit is split between both bulbs. Eg headlights
How does current flow when drawing a circuit
From positive to negative , although it’s not acc like that
Conductors
Allow electricity to flow through themselves eg metal
Insulators
Do not allow electricity to flow through themselves
How to arrange a voltage circuit
In parallel with the component (bulb)
Ohm’s law equation
Triangle : Voltage on top
Current (|) and Resistance (R) on bottom
Ohm’s law
For a metallic conductor at constant temperature the current is directly proportional to the voltage
Diode
A device that allows current to flow in one direction only.
In a diode symbol, which side is the positive
The one with the triangle
LDR
Light dependent resistor : changes resistance with the amount of light falling on it
At low light , resistance is high.
Used in street lights
Thermistor
A resistor whose resistance can be changed by changing its temperature
When cold, resistance is high
Used in fire alarms, fridges
How to measure electrical power
The amount of electrical energy converted to other forms in one second
Unit of power
Watt (P)
What do you use to measure the power of an appliance
Wattmeter
Power equation is
Power = voltage x current (|)
What is current measured in units
Amps (A) but the symbol is |
